In an image forming apparatus, a near empty state indicating that a toner will run out in a short time is displayed before a display indicating that the toner is empty is made. A user can order a new toner at a timing at which the near empty state is displayed. By displaying the near empty state as described above, the image forming apparatus can be used continuously without occurrence of shortage of the toner.
As a conventional method for determining the near empty state, a method using a sub hopper is known. The sub hopper is a container provided between a developing device and a toner cartridge. The sub hopper is provided with a sensor for detecting an amount of toner. If the amount of toner does not reach a threshold value, it can be determined that the toner cartridge is in a near empty state. For example, in such a state, it is determined that the image forming apparatus is in the near empty state.
However, in the method using the sub hopper, it is necessary to provide the sub hopper. In the sub hopper, it is also necessary to provide a toner sensor only used for determining the near empty state. Therefore, there is a problem that the cost increases in the method using such a sub hopper.